Interestingly I heard that it's not that they're less technology skilled exactly (I'm not commenting that I'd or isn't the case), but instead grown up on a different platform, notably iPhone/iPad/android instead of a PC.
This has meant a big push by companies to develop mobile first. So much so, some companies don't even have a browser version of their system anymore.
Yeah they've always been able to just long press on a file to mark a batch of files to be sent. Any use cases for archives they had were solved adequately by this. However, those aren't better solutions. There are other use cases for archives which those systems can't solve. The companies you point out that develop mobile-only, are hamstringing themselves IMO. I can think of a couple of occasions where I've disengaged with a company specifically because they pushed all possible interactions through their app with no redundancy, and then some function in the app didn't work